The present invention provides crystals of an adduct of a bisphenol and phenol, a process for preparing these crystals and a process for preparing bisphenols.
Bis(4-hydroxyaryl)alkanes, in the following called bisphenols, are important as starting materials or as intermediates for preparing a number of commercial products. Bisphenols can be prepared by the condensation of phenols and carbonyl compounds. Substituted phenols or unsubstituted phenol may be used.
The condensation product from the reaction between phenol and acetone, 2,2-bis(4 hydroxyphenyl)propane (bisphenol A, BPA,) is of particular industrial importance. BPA is used as a starting material for preparing various types of polymer materials such as, for example, polyarylates, polyetherimides, polysulfones and modified phenol/formaldehyde resins. Preferred areas of application are the preparation of epoxy resins and polycarbonates.
Processes for preparing bisphenols by acid-catalysed reaction of phenols with carbonyl compounds are known, for example from U.S. Pat. No. 2,775,620 and from EP-A-0 342 758.
Bisphenols of general structure can be prepared by processes which are analogous to the preparation of BPA.
Bisphenols can be prepared via an adduct of bisphenol and phenol as an intermediate stage.